Unit Six: Blood Cells, Immunity, and Blood Coagulation Chapter 32: Red Blood Cells, Anemia, and Polycythemia Guyton and Hall, Textbook of Medical Physiology, 12th edition

Red Blood Cells Red Blood Cells (Erythrocytes) Transport hemoglobin Contain carbonic anhydrase (acid-base buffering) Shape and size of rbcs-pliable Concentration in the blood- 40-45% Quantity of hemoglobin in the cells- 14-15 g/100 ml of cells

Production of Red Blood Cells Fig. 32.1 Relative rates of rbc production in the bone marrow of different bones at different ages

Pluripotential Hematopoietic Stem Cells Genesis of Blood Cells Pluripotential Hematopoietic Stem Cells Fig. 32.2

Stages of Differentiation of RBCs Genesis of Blood Cells Stages of Differentiation of RBCs Fig. 32.3

Red Blood Cells (cont.) Regulation of RBC Production-Erythropoietin Tissue oxygenation is the most essential regulator of rbc production Erythropoietin stimulates rbc production, and its formation increases in response to hypoxia Role of the kidney-90% of the erythropoietin is formed in the kidney (liver-10%)

Red Blood Cells (cont.) Fig. 32.4 Function of the erythropoietin mechanism to increase production of rbcs when tissue oxygenation decreases.

Red Blood Cells (cont.) Maturation of RBCs Requirement for Vitamin B12 and Folic acid Maturation failure with poor absorption of B12-leads to pernicious anemia Maturation failure with poor absorption of Folic acid- leads to sprue (usually occurs in association with the vitamin deficiency

Formation of Hemoglobin Red Blood Cells (cont.) Formation of Hemoglobin Fig. 32.5 Formation of hemoglobin Fig. 32.6 Basic structure of hemoglobin

Red Blood Cells (cont.) Iron Metabolism Transport and storage of iron- transferrin, ferritin Daily loss of iron (0.6 mg/day; feces) Absorption of iron from the GI tract Regulation of total body iron by controlling the rate of absorption

Red Blood Cells (cont.) Iron Metabolism Fig. 32.7 Iron transport and metabolism

Red Blood Cells (cont.) Life Span of RBCs is about 120 Days Destruction of Hemoglobin Fe is carried by transferrin to bone marrow Fe is stored as ferritin Porphyrin ring is converted to bilirubin

Anemias Blood Loss Anemia- hemorrhage Aplastic Anemia- lack of functioning bone marrow Megaloblastic Anemia- slow reproduction of erythroblasts Hemolytic Anemia- abnormalities of rbcs Effects on the Circulatory System- low blood viscosity, decreased resistance to blood flow, increased CO, increased workload on the heart

Polycythemia Secondary Polycythemia- abnormal quantities of rbcs Polycythemia vera (Erythremia)- genetic aberration Effects on the Circulatory System- CO and arterial pressure is normal, blood is sluggish passing through the capillaries and skin color may take on a bluish cast